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UNITED STATES i n rcnar UFFICEQ GEORGE A. CARDVELL, OF BROOKLYN, N. Y.,ASSIGNOR TO HIMSELF, FRED- ERICK K. FITCH, OE NEYV YORK, N.

NEWARK, N. J.

TELEGRAPHIC AND TEL PHD:

SPECIFICATION fcrming part of Y., AND JOSEPH T. MURRAY, OE

EC i" PRD'TECTOR.

Application tiled Fclnnaiy 1-1, 1884. (No model.)

To aZZ whom it may concern:

Be it known that I, GEORGE A. CARDWELL, of the city of Brooklyn, countyof Kings, and State of New York, have invented certain new 5 and usefulImprovements in Telegraphic and Telephonic Instrument Protectors; and Ido hereby declare the following to be a full, clear, and exactdescription of the invention.

This invention has for its object the provision and maintenance duringits necessity of means for protecting telegraphic, telephonic, and otherelectrical instruments against ini u ry arising from the introductioninto their circuits of abnormallypowerful currents oteleetricity. Myinvention consists of an electrical apparatus designed to be placed incircuit with the IlllStlllll'lBlltS to he protcetel, and of such natureand construction as not to be affected or energized by the normaloperating-current; but when a powertul current is acciden allyintroducedas,for instance, by the line-wires coming in contact withwires conducting currents tor elec. ric lightingthe apparatus will be sooperated as to immediately break the circnitof the workinginstrumentsandground the dangerous current. The apparatus is also so arranged that itwill automatically restore the circuit to its normal condition when thedangerous current has been eliminated.

The drawing represents a top view of theapparatus,part-lyinsection,showingtheconstruction and arrangement oftheseveral component parts. Upon an ordinary base, A, are secured twoelectro-magnets, N and M, with their arma- 5 tures it and m hinged,respectively, atrand r.

a and m are the cores of the magnets, and n and m" are the outsideextensions of the iron core. The armatures m and n have each at theirinner ends a short piece of metal, or m. separated by strip ofinsulating material 00 rt from the main piece of the armature. Thearmature a is provided with the back contact point, 0, and the armaturem with the back contact-points, c and e. 0 and c are kept in 4.5 contactwith the ends of the adjustingscrews t and t by the retractive force otthe springs s s, which are attached to the arm atures and toadjusting-screws F F, working in suitable pieces secured to the base.Thesescrews allow of the graduation of the strength of the springsaccording to the strength of the current normally passing hrough theline. The springs must be ol'such strength that the armaturcs will notbe drawn toward the magnets except when energized by currents much morepowerful than the workingcurrcnt of the line. The adjusting-screws t tworkin angle-pieces secured to the base-plate, the same pieces alsocarrying binding-posts T T, to which are attached the \VlitS t 1,connecting with the instruments which it is desired to protect. Betw eenthe two electro-magnets a metal plate, E, is secured, having abindingpost, G, directly connected with ground. In the upper part of theplate E three screws, 0 (Z work. These screws are respectively oppositethe contact points 0 on the lower side of the insulated end a of thearmature n, the contactpoint i? on the spring is, and the contact-pointd on the lower side of the armature m.

.v'hen the instrument is not-in use, or the currentis normal,thecontactpoint i is almost, but not quite, in contact with the platinumpoint ot'screw t", the contact-point 0 is a little farther separatedtrom the screw 0", and-tl1e contactpoint (l is still more widelyseparated. Screws are used. so that these points may be kept in correctadjustment.

The wire used in winding the magnet M is in two sectionsiinc wire \V andcoarse wire to. The line wire wound in the usual manner next to thesol'tiron core, and is for the purpose ot'cnergizing the magnet morequickly than it the magnet were composed of coarse wire only. "he othersection, which is not continuous with the first, but composes a part ofthe same circrit, is wound with very coarse wire. Both these coils orpart of a coil of electro-magnet ll are in the normal circuit. Theinstrument or instruments to be protected are inserted between themthatis, they are each connected to the instruments in such a way that thenormal current passes through one part of this double coil, then throughthe illstruments. and tinally through the other part of the double coil.\Vhen an abnormal current enters the line, it for an instant pursues thesame course; but almost immediately the fine-wire part of the coil iscut out and the current passes entirely throu h the large wire. To thebindingposts L L are attached the line-wires Z Z. The core of magnet Nis surrornded with coarse wire only, wound in the usual manner. It isbrought into use only when the abnormal current enters at L. Thecontacts at t and c are made by the screw and a platinum contact-pointon m and two opposite points attached to a small springplate, K, securedto the block 76, which is insulated. At 0 the points are normally incontact, while at 1' they are slightly separated.

The connections are as follows: One of the line-wires enters thebinding-post L. This binding-post is connected to one end of the coil ofthe electromagnet N. The other end of this coil is connected with theinsulated end a" of the armature a. This in turn is connected by acovered wire with the insulated end on of armature m. The line-wireentering at binding-post L is connected with the outside of thecoarse-wire coil of electro-n'iagnet M. The other end of this coil isattached to the armature in. A connection is made between thebinding-post L and the inner end of the fine-wire coil of M. The outerend of the fine-wire coil is connected with the armature a. Thebinding-post G connects with ground. The instruments are connected bymeans of binding-posts T and T. The normal circuit is beginning at Lthrough the coarse wire of magnet M to armature at through contactc toT, thence through the instrument or instruments to be protected to T,and on through contact a, armature a, to the fine wire of magnet M,thence to line through post L. Should a powerful current gain access tothe line, and enter the apparatus at L, magnet M is instantaneouslyenergized. Armature m is drawn down, the contact at c is broken, cuttingout line-instrument, the contact at d is made, and ground-circuitcompleted. As soon as circuit is closed the coarse wire of M takes thewhole abnormal charge direct to earth by way ofm d (I G, &c. \Vhen theline is relieved, m is drawn back by the spring 8, contact 0 is closed,and the line is again in normal condition. Should the heavy currententer the apparatus from the opposite direction at L, it energizes themagnet M by entering the tinewire section by means of the wire Z), andoperates the armature m, as before. The contact at c is broken, thecontact at i on the spring K is made. The breaking of the contact 0 cutsout the magnet M, demagnetizing it, and of course releases the armaturem, which in receding closes the contact 0 on the spring K before thecontact i is broken, forming a temporary ground circuit through magnetX, insulated end a of ar1nature a, contact at 0, between spring K andinsulated end at of armature at, contact at '17, between spring K andscrew 1', attached to ground-plate E, and grouml-plate E to ground. Thecurrent now passing through N energizes it, and draws down the armaturea and forms a direct ground-circuit through a, contact 0, andground-plate E.

By the use oi my device the entire abnormal current is diverted toground. In most of the instrnmentsin use the current divides, a portiongoing over the line, though the larger part goes to ground.

Having now fully described my invention, what I claim, and desire tosecure by Letters Patent, is-

1. In an electromagnetic device for protecting electrical instrumentsfrom abnormal currents, two electro-magnets, one wound with coarse wireonly and not normally in circuit, the other wound with two separatenon-coir tinuous superposed coils, one ol'iii'ie'wire and the other ofcoarse wire, but both coils in the same normal circuit, the instrumentsto be protected being interposed between the coils or parts of a coil,substantially as shown and described.

2. In an electromagnetic device for protecting electrical instrumentsfrom abnormal cnrrents, conducting armatures of two electromagnetshaving insulated ends electrically comiccted but mechanicallyindependent, substantially as shown and described.

3. In an electromagnetic device for theprotcction of electrical.instruments from abnormal currents,an insulated independentspring, K,having two contact-points, one, 0, normally in contact with theinsulated portion m of an armature, m, of an electro-magnet in thenormal circuit, while the other, 2, is separated from the groundcontactpoint by aslight interval, substantially as shown and described.

4. In an electromagnetic apparatus for pro tecting electricalinstrumein's from abnormal currents, the combination of clectro-nn'ignetN, electro-magnet M, with two coils, one of fine and the other of coarsewire, the armatnres a and m, having insulated metallic ends a and m,retracting springs s s, spring K, groi'uid-plate In, and contact-pointsc, c, c, 47, and'd, substantially as shown and described.

In witness whereof I have hereunto set my hand.

GEORGE A. CARDW'ELL.

\Vitnesses:

Gno. II. Soxxnnonrv, Farm; Hiininsos'.

TOO

